Proceedings Paper
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Spatial bandwidth limitations frequently introduce large biases into the estimated values of RMS roughness and
autocorrelation length that are extracted from topography data on random rough surfaces. The biases can be particularly
severe for focus-variation microscopy data because of the technique’s spatial bandwidth limitations (limited lateral
resolution and field-of-view). We recently developed a measurement protocol that greatly reduces the bias due to limited
resolution[1]. In the present paper, we describe an extension of the protocol to correct for limited field-of-view, and present
measurements on a series of commercial surface roughness comparator samples to validate the protocol. The protocol
strictly applies to the case of surfaces that are isotropic, and whose topography displays an autocovariance function that is
exponential, with a single autocorrelation length. However, we find that applying the protocol yields extracted values of
roughness and autocorrelation length for each surface that are accurate and consistent among datasets obtained at different
magnifications (i.e. among datasets obtained with different spatial bandpass limits), even for samples that are not in any
way selected to conform to the model’s assumptions.